JP2015190815A - Lithium ion secondary battery state detection system and lithium ion secondary battery state detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery state detection system capable of accurately determining a deterioration state of a battery.SOLUTION: A lithium ion secondary battery state detection system comprises: detection means 103, 101 detecting that an SOC of a lithium ion secondary battery 201 mounted in an electric vehicle 200 is 0%; electric discharge means 101 discharging the lithium ion secondary battery 201 until it is detected that the SOC is 0% and supplying discharge power to an external load 300; charging means 101, 104, 110, 120 charging the lithium ion secondary battery 201 until the SOC is equal to a predetermined value after electric discharge; resistance measuring means 105, 103, 101 applying a current to the lithium ion secondary battery 201 in a state in which the battery 201 is charged by the charging means 101, 104, 110, 120, and calculating a battery resistance by measuring a voltage change due to the application of the current; and deterioration state determination means 101 determining a deterioration state of the lithium ion secondary battery 201 based on the calculated battery resistance.

Description

  The present invention relates to a state detection system and a state detection method for a lithium ion secondary battery, and more particularly to a state detection system and a state detection method for a lithium ion secondary battery mounted on an electric vehicle.

  In recent years, attention has been focused on the introduction of electric vehicles (EV) and hybrid electric vehicles (HEV) in order to reduce carbon dioxide emissions for the purpose of environmental protection. In order to spread these electric vehicles, it is important to accurately grasp the performance of the lithium ion secondary battery that changes with time due to deterioration.

  On the other hand, accurate measurement of battery capacity and battery resistance, which are the performance of lithium ion secondary batteries when mounted on an electric vehicle, can stably charge and discharge the secondary battery and apply voltage to the electric vehicle. Is generally difficult because it is impossible.

  As a conventional technique for measuring the battery capacity of a secondary battery that changes with time due to deterioration of a single lithium ion secondary battery, there are those described in the following prior art documents. That is, the previously calculated battery capacity is replaced with the battery capacity calculated based on the integrated current value of the discharge current until the secondary battery is completely discharged. Thereby, there is a battery capacity that can be grasped even if the battery capacity, which is the performance of the secondary battery, changes with time.

JP 2002-325362 A

  However, although the above-mentioned conventional technology can measure the battery capacity that changes with time, there is a problem in that the deterioration state of the secondary battery cannot be accurately determined based on the battery resistance when mounted on the electric vehicle. is there.

  The present invention has been made to solve such problems. That is, a battery resistance is measured with high accuracy by applying a current and measuring a voltage change in a state where a lithium ion secondary battery mounted on an electric vehicle is accurately charged to a predetermined SOC (State Of Charge). The purpose is to make it possible to accurately determine the deterioration state of the.

  The above problem is solved by the following means.

  A state detection system for a lithium ion secondary battery, which includes a detection unit, a discharge unit, a charging unit, a resistance measurement unit, and a deterioration state determination unit. The discharging means discharges the lithium ion secondary battery mounted on the electric vehicle until the detecting means detects that the SOC is 0%, and supplies the discharged power to the external load. The charging means charges after the discharging by the discharging means until the SOC reaches a predetermined value. The resistance measuring unit calculates the battery resistance by applying a current to the lithium ion secondary battery in which the SOC is set to a predetermined value and measuring a voltage change due to the current application. The deterioration state determination means determines the deterioration state of the battery based on the calculated battery resistance.

  A method for detecting a state of a lithium ion secondary battery, wherein the lithium ion secondary battery mounted on the electric vehicle is discharged until the SOC is detected to be 0%, and the discharge power is externally supplied. Supply to the load. After the discharge, the battery is charged until the SOC reaches a predetermined value, a current is applied to the lithium ion secondary battery in which the SOC is set to the predetermined value, and a battery resistance is calculated by measuring a voltage change due to the applied current, and is calculated. The deterioration state of the battery is determined based on the battery resistance.

  After discharging the lithium ion secondary battery mounted on the electric vehicle until the SOC reaches 0%, the battery resistance is increased by measuring the voltage change by applying a current with the SOC accurately charged to the predetermined SOC. By measuring accurately, the deterioration state of the battery can be accurately determined.

1 is a configuration diagram of a state detection system for a lithium ion secondary battery according to a first embodiment of the present invention. It is a schematic sectional drawing which shows typically the example of the structure of a lithium ion secondary battery. It is explanatory drawing of the measuring method of the battery capacity of a lithium ion secondary battery. It is a flowchart which shows operation | movement of the state detection system which concerns on 1st Embodiment of this invention. It is a figure which shows the charge condition of the lithium ion secondary battery corresponding to the flowchart of FIG. It is a flowchart which shows operation | movement of an electric vehicle. It is a flowchart which shows operation | movement of the state detection system which concerns on 2nd Embodiment of this invention. It is a figure which shows the charge condition of the lithium ion secondary battery corresponding to the flowchart of FIG.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  FIG. 1 is a configuration diagram of a state detection system for a lithium ion secondary battery according to the present embodiment. In FIG. 1, together with the state detection system 1, an electric vehicle 200 connected to the state detection system 1 and a house 300 that is an external load are shown.

  As shown in FIG. 1, the state detection system 1 includes a state detection device 100 and a commercial power source 110.

  The commercial power supply 110 is a facility for supplying power from an electric power company to a power consumer, and supplies power to the state detection device 100 by being connected to the state detection device 100.

  The state detection device 100 includes an arithmetic control unit 101, a storage unit 102, a voltmeter 103, an ammeter 104, a converter 120, and switches S1 to S3. The voltmeter 103 and the calculation control unit 101 constitute detection means. The arithmetic control unit 101 constitutes a discharging unit, a deterioration state determining unit, and a first updating unit. The commercial power supply 110, the converter 120, the ammeter 104, and the calculation control unit 101 constitute a charging unit. Converter 120, voltmeter 103, and arithmetic control unit 101 constitute resistance measuring means.

  Voltmeter 103 measures the battery voltage of battery 201 by being connected to a lithium ion secondary battery 201 (hereinafter simply referred to as “battery 201”) mounted on electric vehicle 200. The voltmeter 103 transmits the measured battery voltage data to the calculation control unit 101.

  Here, in FIG. 1, dotted arrows indicate directions in which various data are transmitted.

  The ammeter 104 measures the charging current Ic supplied to the battery 20 by being connected between the battery 201 and the converter 120. The ammeter 104 transmits the measured charging current Ic data to the calculation control unit 101.

  Converter 120 converts AC power input from commercial power supply 110 into DC power and outputs it to battery 210. The converter 120 can be configured by, for example, an AC / DC converter.

  Converter 120 further supplies pulse current as a direct current for a short time to battery 201. Converter 120 can generate a pulse current using AC power input from commercial power supply 110 and supply the pulse current to battery 201. In addition to the converter 120, a current application device (not shown) may be provided to supply a pulse current to the battery 201 by the current application device. In this case, the current application device can be constituted by a current pulse generator.

  The amplitude and pulse width of the pulse current are not limited. For example, the amplitude can be 20 A and the pulse width can be 10 seconds.

  The calculation control unit 101 controls each component of the state detection system 1 and performs various calculations. The arithmetic control unit 101 can be configured by a single or a plurality of semiconductor chips and programs on which an arithmetic control device, a storage device, and an input / output device, which are components of a computer, are mounted.

  Arithmetic control unit 101 controls the connection state of commercial power supply 110, converter 120, ammeter 104, house 300, and electric vehicle 200 by controlling the conduction / non-conduction of switches S <b> 1 to S <b> 3.

  The arithmetic control unit 101 receives the voltage of the battery 201 measured by the voltmeter 103 and detects that the SOC is 0% based on the voltage of the battery 201. The arithmetic control unit 101 can detect that the SOC is 0% when the voltage of the battery 201 reaches the lower limit voltage set in advance by discharging. The lower limit voltage is a battery voltage when the SOC is estimated to be 0% based on the characteristics of the battery 201. For example, the battery 201 is a stacked lithium ion secondary battery in which unit cells are connected in series. In this case, it can be set to 2.5 V in terms of the voltage of a single battery cell.

  The arithmetic control unit 101 detects the SOC of the battery 201 by calculating it. The arithmetic control unit 101 receives the charging current Ic to the battery 201 from the state in which the SOC of the battery 201 is determined to be 0% until the SOC is determined to be 100% from the ammeter 104, and calculates the integrated current value of the charging current Ic. By calculating, the battery capacity of the battery 201 can be accurately calculated. Further, the calculation control unit 101 calculates the integrated current value of the charging current Ic from the state in which the SOC of the battery 201 is determined to be 0%, and accurately calculates the SOC of the battery 201 as the ratio of the integrated current value to the battery capacity. can do. Therefore, the arithmetic control unit 101 can accurately set the SOC of the battery 201 to a predetermined value. The predetermined value of the SOC can be set to 50%, for example.

  The arithmetic control unit 101 applies a pulse current to the battery 201 by the converter 120 in a state where the SOC of the battery 201 is set to a predetermined value, and causes the voltmeter 103 to measure a voltage change of the battery 201 due to the application of the pulse current. . The arithmetic control unit 101 calculates the battery resistance of the battery 201 by dividing the measured voltage change (voltage amplitude) of the battery 201 by the amplitude (current amplitude) of the pulse current applied to the battery 201. The battery resistance can be measured with high accuracy by measuring the voltage change by applying the pulse current in a state where the predetermined SOC is accurately set. In addition, since a direct current is applied to the battery 201 for a short time by applying the pulse current, it is possible to suppress the deviation of the SOC from a predetermined value due to the current application and further improve the accuracy of the measured battery resistance. Can be made.

  As the battery 201 deteriorates, a film is generated mainly on the negative electrode, the battery resistance increases, and the battery capacity decreases. The arithmetic control unit 101 determines the deterioration state of the battery 201 by calculating the battery capacity based on the battery resistance using a map that defines the relationship between the battery resistance and the battery capacity stored in the storage unit 102. can do. The arithmetic control unit 101 may determine the deterioration state of the battery 201 based on the battery resistance. The arithmetic control unit 101 may transmit a warning to the electric vehicle 200 when the calculated battery capacity is below a preset threshold value or when the battery resistance is above a preset threshold value.

  When the SOC is reduced to 0% by discharging the battery 201, the arithmetic control unit 101 can supply electric power used in the house 300 to the house 300 by outputting the discharge current Id to the house 300. . As a result, the discharge current Id can be used effectively while accurately measuring the battery resistance by accurately setting the SOC of the battery 201 to a predetermined value. The discharge current Id may be converted into an alternating current by the converter 120 and output to the house 300.

  The arithmetic control unit 101 transmits the calculated battery resistance data of the battery 201 to the electric vehicle 200 to update the battery resistance data of the electric vehicle 200.

  The storage unit 102 stores various programs and various data. The storage unit 102 can be configured by, for example, an HDD (Hard Disk Drive).

  The storage unit 102 stores a program executed by the arithmetic control unit 101.

  The storage unit 102 stores data on the battery capacity, remaining battery capacity (SOC), and battery resistance values calculated by the arithmetic control unit. Furthermore, the memory | storage part 102 memorize | stores the map which prescribes | regulates the relationship between battery resistance and battery capacity. A map that defines the relationship between the battery resistance and the battery capacity may be stored for each product type of the battery 201.

  The switches S <b> 1 to S <b> 3 change the connection state of the commercial power supply 110, the converter 120, the ammeter 104, the house 300, and the electric vehicle 200 by being turned on or off by control by the arithmetic control unit 101. The switches S1 to S3 can be configured by, for example, a semiconductor switch having an appropriate current capacity and withstand voltage.

  Here, the electric vehicle 200 equipped with the battery 201 that is charged or discharged by being connected to the state detection system 1 will be described.

  The electric vehicle 200 includes a battery 201, a calculation control unit 202, a storage unit 203, a display unit 204, a current sensor 207, an inverter 205, and a motor 206. The arithmetic control unit 202, the current sensor 207, and the storage unit 203 constitute a second update unit.

  FIG. 2 is a schematic cross-sectional view schematically showing an example of the structure of a lithium ion secondary battery. As shown in FIG. 2, the battery 201 has a structure in which a power generation element 21 that performs charging and discharging is sealed inside an exterior body 29.

  As shown in FIG. 2, the battery 201 has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside an exterior body 29. Here, the power generation element 21 has a configuration in which a positive electrode, a separator 17, and a negative electrode are stacked. The positive electrode has a structure in which the positive electrode active material layers 15 are disposed on both surfaces of the positive electrode current collector 12. The negative electrode has a structure in which the negative electrode active material layer 13 is disposed on both surfaces of the negative electrode current collector 11. Specifically, the negative electrode (the negative electrode current collector 11 and the negative electrode active material layer 13) is formed such that one positive electrode active material layer 15 and the negative electrode active material layer 13 adjacent thereto face each other with a separator 17 therebetween. The separator 17 and the positive electrode (the positive electrode current collector 12 and the positive electrode active material layer 15) are laminated in this order. As a result, the adjacent negative electrode, separator 17 and positive electrode constitute one single cell layer 19. As a result, each unit cell is configured to be electrically connected in parallel.

  The positive electrode current collector 12 and the negative electrode current collector 11 are each provided with a positive electrode current collector plate (tab) 27 and a negative electrode current collector plate (tab) 25 that are electrically connected to the respective electrodes (positive electrode and negative electrode). It has the structure led out of the battery exterior material 29 so that it may be pinched | interposed into the edge part. The positive electrode current collector 27 and the negative electrode current collector 25 are ultrasonically welded to the positive electrode current collector 12 and the negative electrode current collector 11 of each electrode, respectively, via a positive electrode lead and a negative electrode lead (not shown) as necessary. Or resistance welding or the like.

[Current collector]
There is no particular limitation on the material constituting the current collectors 11 and 12, but a metal is preferably used.

  Specifically, examples of the metal include aluminum, nickel, iron, stainless steel, titanium, copper, and other alloys. In addition to these, a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plating material of a combination of these metals can be preferably used. Moreover, the foil by which aluminum is coat | covered on the metal surface may be sufficient. Of these, aluminum, stainless steel, and copper are preferable from the viewpoints of electronic conductivity and battery operating potential.

  The size of the current collectors 11 and 12 is determined according to the intended use of the battery. For example, if it is used for a large battery requiring high energy density, a current collector having a large area is used. There is no particular limitation on the thickness of the current collector. The thickness of the current collector is usually about 1 to 100 μm.

[Positive electrode active material layer]
The positive electrode active material layer 15 includes a positive electrode active material capable of accumulating and releasing a substance (ion) that travels between the positive electrode active material layer 15 and the negative electrode active material layer 13 in an electrode reaction. For example, when the battery 201 is a lithium ion secondary battery, a lithium-transition metal composite oxide is preferable. As the positive electrode active material, a Li · Co composite oxide such as LiCoO ₂ or a Li · Co composite oxide such as LiNiO _{2 is} used. Ni-based composite oxide, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, or the like can be used Li · Fe-based composite oxides such as LiFeO _2. In addition, transition metal oxides such as LiFePO ₄ and lithium phosphate compounds and sulfate compounds, transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ , PbO ₂ , AgO, NiOOH or the like can be used. In some cases, two or more positive electrode active materials may be used in combination.

  The conductive auxiliary agent contained in the positive electrode active material layer 15 has a function of improving the conductivity of the positive electrode active material. For example, carbon powder such as graphite and various carbon fibers such as vapor grown carbon fiber (VGCF). It consists of.

  The binder contained in the positive electrode active material layer 15 functions as a binder between the positive electrode current collector 12 and the positive electrode active material layer 15. For example, as a binder, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethernitrile (PEN), polyimide (PI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or a mixture thereof can be used.

[Negative electrode active material layer]
The negative electrode active material layer 13 includes a negative electrode active material, a conductive additive, a binder, and the like.

  The negative electrode active material layer 13 includes a negative electrode active material capable of accumulating and releasing a substance (ion) that travels between the positive electrode active material layer 15 and the negative electrode active material layer 13 in an electrode reaction. For example, a carbon material is preferable as the negative electrode active material. Examples of the carbon material include graphite-based carbon materials (graphite) such as natural graphite, artificial graphite, and expanded graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, and hard carbon. More preferably, graphite such as natural graphite, artificial graphite, and expanded graphite can be used. As natural graphite, for example, scaly graphite, massive graphite and the like can be used. As the artificial graphite, massive graphite, vapor-grown graphite, flaky graphite, and fibrous graphite can be used. Among these, particularly preferable materials are scale-like graphite and massive graphite. The use of flaky graphite or massive graphite is particularly advantageous because the packing density increases. In some cases, two or more negative electrode active materials may be used in combination.

  The conductive additive contained in the negative electrode active material layer 13 has a function of improving the conductivity of the negative electrode active material. For example, carbon powder such as graphite and various carbon fibers such as vapor grown carbon fiber (VGCF). It consists of.

  The binder contained in the negative electrode active material layer 13 has a function as a binder between the negative electrode current collector 11 and the negative electrode active material layer 13 and is made of, for example, polyvinylidene fluoride (PVdF). In addition to a solvent-based binder such as polyvinylidene fluoride, a water-based binder (for example, styrene-butadiene rubber) in which polymer fine particles and a rubber material are dispersed in water may be used.

[Separator]
The separator 17 is provided between the positive electrode active material layer 15 and the negative electrode active material layer 13 and electrically isolates the positive electrode active material layer 15 and the negative electrode active material layer 13. The separator 17 holds an electrolytic solution between the positive electrode active material layer 15 and the negative electrode active material layer 13 to ensure ion conductivity. For example, the separator 17 uses a porous film made of polyolefin such as polypropylene (PP) or polyethylene (PE), a porous film made of ceramic, or the like. Moreover, you may use the aramid etc. which have heat resistance.

The electrolytic solution is a non-aqueous (system) electrolytic solution. Ions move between the positive electrode active material layer 15 and the negative electrode active material layer 13 through the electrolytic solution, so that the electricity stored in the power generation element 21 is charged and discharged. For example, the electrolytic solution is in a form in which a lithium salt or the like as a supporting salt is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it can sufficiently dissolve the supporting salt. For example, (1) cyclic carbonates such as propylene carbonate and ethylene carbonate, (2) chains such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate. (3) ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, (4) lactones such as γ-butyrolactone, (5) Nitriles such as acetonitrile, (6) Esters such as methyl propionate, (7) Amides such as dimethylformamide, (8) One or two kinds selected from methyl acetate and methyl formate Plasticizers such as aprotic solvents mixed with the above It is. These organic solvents may be used alone or in combination of two or more. Conventionally known salts are used as the supporting salt. For example, Li (C ₂ F ₅ SO ₂ ) ₂ N (LiBETI), LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N or the like is used.

[Current collector]
The material constituting the current collecting plates 25 and 27 is not particularly limited, and a known highly conductive material conventionally used as a current collecting plate for a lithium ion secondary battery can be used. As a constituent material of the current collector plate, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoint of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferable, and aluminum is particularly preferable. Note that the positive electrode current collector plate 25 and the negative electrode current collector plate 27 may be made of the same material or different materials.

[Exterior body]
The exterior body 29 is composed of, for example, a laminate sheet having a metal plate therein, and covers and seals the power generation element 21 from both sides. Thereby, the exterior body 29 accommodates the power generation element 21.

  Returning to FIG. 1, the calculation control unit 202 controls each component of the electric vehicle 200 and performs various calculations. The arithmetic control unit 202 can be configured by a single or a plurality of semiconductor chips and programs on which an arithmetic control device, a storage device, and an input / output device, which are components of a computer, are mounted.

  The arithmetic control unit 202 receives the battery resistance data of the battery 201 from the state detection system 1 and updates the data stored in the storage unit 203 to the received battery resistance data.

  The calculation control unit 202 calculates the remaining battery capacity of the battery 201 and the travelable distance based on the remaining battery capacity based on the updated value of the battery resistance of the battery 201 and causes the display unit 204 to display the calculated battery remaining capacity. Specifically, for example, the arithmetic control unit 202 uses a map that defines the relationship between the battery resistance and the battery capacity stored in the storage unit 203 based on the updated value of the battery resistance, and uses the battery capacity. Is calculated. The calculation control unit 202 uses a map that defines the relationship between the battery capacity and the travelable distance stored in the storage unit 203 based on the calculated battery capacity, and the travelable distance when the SOC is 100%. Is calculated. The calculation control unit 202 calculates the travelable distance based on the current remaining battery capacity by subtracting the distance actually traveled by the electric vehicle 200 from the calculated travelable distance when the SOC is 100%. The arithmetic control unit 202 detects the amount of electricity consumed when the electric vehicle 200 actually travels from the state where the SOC is 100% by the current sensor 207, and subtracts the detected amount of consumed electricity from the calculated battery capacity. The remaining battery capacity can be calculated.

  The battery remaining capacity of the battery 201 and the travelable distance based on the remaining battery capacity calculated by the arithmetic and control unit 202 in this way are reflected by the battery resistance of the battery 201 being updated. ing. Therefore, the user of the electric vehicle 200 displays the remaining battery capacity of the battery 201 and the travelable distance based on the remaining battery capacity on the display unit 204, so that the remaining battery capacity of the battery 201 and the travelable distance based on the remaining battery capacity are displayed. Can be grasped accurately.

  The storage unit 203 stores a program executed by the arithmetic control unit 202 and various data. The storage unit 203 can be configured by, for example, a flash memory.

  The storage unit 203 stores a map that defines the relationship between the battery resistance and the battery capacity, and a map that defines the relationship between the battery capacity and the travelable distance, and the battery capacity of the battery 201 calculated by the arithmetic control unit 202, The remaining battery capacity and the travelable distance of the electric vehicle 200 based on the remaining battery capacity are stored.

  The display unit 204 displays the remaining battery capacity of the battery 201 calculated by the arithmetic control unit 202 and the travelable distance of the electric vehicle 200 based on the remaining battery capacity. The display unit 204 can be configured by a liquid crystal display device, for example.

  Inverter 205 converts the DC voltage output from battery 201 into a three-phase AC voltage.

  Motor 206 receives a three-phase AC voltage from inverter 205 and generates torque for driving electric vehicle 200.

  The operation of the state detection system 1 will be described.

  FIG. 3 is an explanatory diagram of a method for measuring the battery capacity of a lithium ion secondary battery.

  3A to 3D indicate the battery capacity of the battery 201 by the area of the rectangle, and indicate the SOC by the ratio of the area of the hatched portion to the area of the rectangle.

  FIG. 3A shows a state immediately after the SOC of the battery 201 mounted on the electric vehicle 200 is charged to 100% by the state detection system 1.

  B indicates the remaining battery capacity after the battery 201 is discharged by running the electric vehicle 200 in which the SOC of the battery 201 is charged to 100%.

  C shows a state in which the SOC of the battery 201 is discharged to 0% by supplying the discharge current Id from the battery 201 of the electric vehicle 200 to the house 300 by the state detection system 1.

  D shows a state in which the SOC is charged to 100% by the state detection system 1 after the SOC of the battery 201 of the electric vehicle 200 is discharged to 0%. The state detection system 1 is discharged until the SOC of the battery 201 reaches 0%, and then charged until the SOC reaches 100%. At that time, the state detection system 1 measures the charging current Ic with the ammeter 104 from the state where the SOC is 0% to the state where the SOC is 100%, and calculates the integrated current value of the measured charging current Ic. Thus, the battery capacity of the battery 201 can be accurately measured.

  FIG. 4 is a flowchart showing the operation of the state detection system. FIG. 5 is a diagram showing a state of charge of the lithium ion secondary battery corresponding to the flowchart of FIG. In FIG. 5, as in FIG. 3, A to D indicate the battery capacity of the battery 201 by the rectangular area, and indicate the SOC by the ratio of the area of the hatched portion to the rectangular area.

  Note that the battery capacity of the battery 201 is calculated by the method shown in FIG. 3 before the operation according to the flowchart of FIG. 4 is performed. By calculating the SOC using the battery capacity calculated by the method, the SOC can be set with higher accuracy when measuring the battery resistance, so that the measurement accuracy of the battery resistance is improved and based on the battery resistance. The battery deterioration state can be determined more accurately. On the other hand, the SOC for measuring the battery resistance may be set by calculating the SOC using the battery capacity according to the product specifications of the battery 201 or the battery capacity measured when the battery 201 is shipped.

  The arithmetic control unit 101 of the state detection device 100 determines whether or not the battery performance measurement mode is set by the user (S401). The battery performance measurement mode is a mode in which when the battery 201 is charged, the battery resistance of the battery 201 is calculated to determine the deterioration state of the battery, and the state detection system 1 is used by the user before the battery 201 is charged. Set for.

  When it is determined that the battery performance measurement mode is not set (S401: NO), the arithmetic control unit 101 charges the battery 201 until the SOC reaches 100% (S409 to S410).

  The arithmetic control unit 101 can charge the battery 201 until the SOC becomes 100% by a CCCV (Constant Current-Constant Voltage) method. That is, the battery 201 is first charged with the charging current Ic having a constant current value, and after reaching the upper limit voltage, the SOC of the battery 201 is reduced by continuing charging while lowering the current value of the charging current Ic in order to maintain the upper limit voltage. It can be charged up to 100%. The upper limit voltage is a battery voltage when the SOC is estimated to be 100% based on the characteristics of the battery 201. For example, the battery 201 is a stacked lithium ion secondary battery in which unit cells are connected in series. In this case, it can be set to 4.2 V in terms of the voltage of a single battery cell.

  When the calculation control unit 101 determines that the battery performance measurement mode is set (S401: YES), it discharges the battery 201 until it determines that the SOC is 0% (S402, S403), and discharge current Id. Is supplied to the house 300. At this time, the switches S1 and S3 in FIG. 1 are turned on, and the other switches S2 are turned off. C in FIG. 5 shows a state in which the battery 201 is discharged until it is determined in step S403 that the SOC is 0%. In addition, since A and B of FIG. 5 have shown the same state as A and B of FIG. 3, respectively, description is abbreviate | omitted.

  The calculation control unit 101 charges the battery 201 with the charging current Ic supplied from the converter 120 until it is determined that the SOC is charged from the 0% state to the 50% state where the SOC is a predetermined value (S404, S405). At this time, the switches S2 and S3 in FIG. 1 are turned on, and the other switches S1 are turned off. FIG. 5D shows a state in which the battery 201 is charged until it is determined in step S405 that the SOC is 50%.

  The calculation control unit 101 calculates the integrated current value of the charging current measured by the ammeter 104 from the state where the SOC of the battery 201 is determined to be 0% in step S403, and calculates the SOC as the ratio of the integrated current value to the battery capacity. By calculating, it is determined that the SOC has reached 50%.

  If the calculation control unit 101 determines that the SOC of the battery 201 is 50%, it stops charging the battery 201. The calculation control unit 101 applies a pulse current to the battery 201 by the converter 120 with the SOC set to 50%, and causes the voltmeter 103 to measure a voltage change of the battery 201 due to the application of the pulse current. The battery resistance of the battery 201 is calculated (S406). At this time, the switches S2 and S3 in FIG. 1 are turned on, and the other switches S1 are turned off.

  Based on the battery resistance of the battery 201 calculated in step S406, the arithmetic control unit 101 calculates the battery capacity using a map that defines the relationship between the battery resistance and the battery capacity stored in the storage unit 102. Thus, the deterioration state of the battery 201 is determined (S407).

  The calculation control unit 101 transmits the calculated battery resistance data of the battery 201 to the electric vehicle 200 to update the battery resistance data of the electric vehicle 200 (S408).

  Arithmetic control unit 101 charges battery 201 until SOC reaches 100% by charging current Ic supplied from converter 120 (S409 to S410). At this time, the switches S2 and S3 in FIG. 1 are in a conductive state, and the other switches S1 are in a non-conductive state.

  The calculation control unit 101 ends the charging of the battery 201 by charging the battery 201 until the SOC reaches 100% (S411).

  The operation of the electric vehicle 200 will be described.

  FIG. 6 is a flowchart showing the operation of the electric vehicle.

  The arithmetic control unit 202 of the electric vehicle 200 determines whether or not the battery resistance data of the battery 201 is received from the state detection system 1 (S601).

  When it is determined that the battery resistance data of the battery 201 has been received (S601: YES), the arithmetic control unit 202 updates the battery resistance data stored in the storage unit 203 to the received data (S602).

  The arithmetic control unit 202 calculates the remaining battery capacity of the battery 201 and the travelable distance based on the remaining battery capacity based on the updated battery resistance (S603).

  The calculation control unit 202 can travel based on the remaining battery capacity of the battery 201 displayed on the display unit 204 and the travelable distance based on the remaining battery capacity calculated in step S603. The distance is updated (S604).

  This embodiment has the following effects.

  After discharging the lithium ion secondary battery mounted on the electric vehicle until the SOC reaches 0%, the battery resistance is increased by measuring the voltage change by applying a current with the SOC accurately charged to the predetermined SOC. By measuring accurately, the deterioration state of the battery can be accurately determined.

  Furthermore, the current applied to the battery when measuring the battery resistance is a pulse current. As a result, since direct current is applied to the battery for a short time, deviation of the SOC from a predetermined value due to current application can be suppressed, the accuracy of the measured battery resistance can be further improved, and the deterioration state of the battery can be further improved. Can be judged accurately.

  Furthermore, by transmitting the calculated battery resistance data to the electric vehicle and updating the battery resistance data of the electric vehicle, it is possible to accurately determine the deterioration state of the battery based on the battery resistance in the electric vehicle. Various parameters such as battery capacity depending on the performance can be accurately calculated.

  Further, based on the updated battery resistance data, the remaining battery capacity displayed by the electric vehicle or the travelable distance based on the remaining battery capacity is updated. As a result, the user can accurately grasp the remaining battery capacity reflecting the deterioration state of the battery and the travelable distance based on the remaining battery capacity.

  Further, when measuring the battery resistance, electric power discharged until the SOC becomes 0% in order to set the SOC to a predetermined value is supplied to the house as electric power used in the house. This makes it possible to effectively use the discharge power while accurately measuring the battery resistance by accurately setting the SOC of the battery to a predetermined value.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the accompanying drawings. The difference between the present embodiment and the first embodiment is as follows. That is, in the first embodiment, the battery resistance is calculated by applying a pulse current in a state where the SOC of the battery 201 mounted on the electric vehicle 200 is set to 50%. The battery resistance is calculated by applying a pulse current with the SOC set to 100%. Since the present embodiment is the same as the first embodiment with respect to other points, the overlapping description is omitted or simplified.

  FIG. 7 is a flowchart showing the operation of the state detection system. FIG. 8 is a diagram showing a state of charge of the lithium ion secondary battery corresponding to the flowchart of FIG. 8A to 8E indicate the battery capacity of the battery 201 by the rectangular area, and indicate the SOC by the ratio of the area of the hatched portion to the rectangular area.

  Before the operation according to the flowchart of FIG. 7 is performed, the battery capacity of the battery 201 is calculated by the method shown in FIG. However, instead of calculating the battery capacity of the battery 201, the battery capacity according to the product specifications of the battery 201 or the battery capacity measured when the battery 201 is shipped may be used.

  The calculation control unit 101 of the state detection device 100 determines whether or not the battery performance measurement mode is set by the user (S701).

  When the calculation control unit 101 determines that the battery performance measurement mode is not set (S701: NO), the battery 201 is charged until the SOC reaches 100% (S707 to S708), and the flowchart is ended.

  When it is determined that the battery performance measurement mode is set (S701: YES), the arithmetic control unit 101 discharges the battery 201 until it is determined that the SOC is 0% (S702, S703). Arithmetic control unit 101 determines that the SOC is 0% because the voltage of battery 201 has reached the lower limit voltage due to the discharge. C in FIG. 8 shows a state in which the battery 201 is discharged until it is determined in step S703 that the SOC is 0%. In addition, since A and B of FIG. 8 have shown the same state as A and B of FIG. 3, description is abbreviate | omitted, respectively.

  The calculation control unit 101 charges the battery 201 until it is determined that the SOC is 100% (S704, S705). The calculation control unit 101 calculates the integrated current value of the charging current measured by the ammeter 104 from the state where the SOC of the battery 201 is determined to be 0% in step S703, and calculates the SOC as the ratio of the integrated current value to the battery capacity. By calculating, it is determined that the SOC is 100%. FIG. 7D shows a state in which the battery 201 is charged until it is determined in step S705 that the SOC is 100%.

  Arithmetic control unit 101 ends charging of battery 201 when SOC of battery 201 reaches 100%. The arithmetic control unit 101 applies a pulse current to the battery 201 by the current application device 105 in a state where the SOC is set to 100%, and causes the voltmeter 103 to measure a voltage change of the battery 201 due to the application of the pulse current. Thus, the battery resistance of the battery 201 is calculated (S706). Note that since the voltage of the battery 201 reaches the upper limit voltage when the SOC is 100%, a pulse current is supplied as a pulse current that is charged after being discharged with a short-time DC current first.

  The arithmetic control unit 101 transmits the calculated battery resistance data to the electric vehicle 200 (S706).

  This embodiment has the following effects.

  After the lithium ion secondary battery mounted on the electric vehicle is discharged until the SOC becomes 0%, the voltage change is measured by applying a current in a state of being charged accurately until the SOC becomes 100%. Thereby, it is possible to accurately determine the deterioration state of the battery by measuring the battery resistance with high accuracy, and it is possible to eliminate the need to stop the charging in the middle of charging the battery and measure the battery resistance.

  As mentioned above, although this invention was demonstrated by embodiment, this invention is not limited to embodiment mentioned above.

  For example, in the above-described embodiment, the battery resistance is measured by applying a pulse current to the battery. However, a direct current that maintains a constant current value may be used instead of the pulse current.

  In the embodiment, in an electric vehicle, the travelable distance when the SOC is 100% is calculated, and the current battery remaining capacity can be traveled by subtracting the distance actually traveled by the electric vehicle from the travelable distance. The distance is calculated. However, when calculating the remaining battery capacity, use the map that defines the relationship between the remaining battery capacity and the travelable distance based on the remaining battery capacity to calculate the possible travel distance based on the remaining battery capacity. May be.

  Moreover, in embodiment, it utilizes by applying the discharge current of a battery to a house. However, (i) charging a storage battery and selling power to a power company at a time when the electricity rate is high, (ii) selling power obtained by illuminating a solar panel with a headlight, or (iv) It may be utilized by electrolyzing water to accumulate hydrogen and later using it for power generation of a fuel cell.

  In the embodiment, part or all of the part executed by the program may be replaced with hardware.

1 status detection system,
100 state detection device,
101 arithmetic control unit,
102 storage unit,
103 Voltmeter,
104 ammeter,
105 current application device,
110 Commercial power supply,
120 converter,
S1, S2, S3, S4, S5 switches,
200 electric vehicle,
201 battery,
202 arithmetic control unit,
203 storage unit,
204 display unit,
300 houses.

Claims (12)

Detecting means for detecting that the SOC of the lithium ion secondary battery mounted on the electric vehicle is 0%;
Discharging means for discharging the lithium ion secondary battery until the detection means detects that the SOC of the lithium ion secondary battery is 0%, and supplying the discharged power to an external load;
Charging means for charging the lithium ion secondary battery until the SOC of the lithium ion secondary battery reaches a predetermined value after the lithium ion secondary battery is discharged by the discharging means;
A current is applied to the lithium ion secondary battery while the lithium ion secondary battery is charged until the SOC reaches the predetermined value by a charging means, and the lithium ion secondary battery is obtained by applying the current. A resistance measuring means for calculating a battery resistance of the lithium ion secondary battery by measuring a voltage change of
A deterioration state determination unit that determines a deterioration state of the lithium ion secondary battery based on the battery resistance calculated by the resistance measurement unit;
A state detection system for a lithium ion secondary battery.   The state detection system for a lithium ion secondary battery according to claim 1, wherein the predetermined value of the SOC is 100%.   3. The state detection system for a lithium ion secondary battery according to claim 1, wherein the current applied by the resistance measuring unit to the lithium ion secondary battery is a pulse current. 4.   The battery resistance data calculated by the resistance measuring means is transmitted to the electric vehicle, and further includes first update means for updating the battery resistance data of the electric vehicle. The state detection system of the lithium ion secondary battery as described in one term.   The electric vehicle is based on the battery resistance data updated by the first updating means, and the battery remaining capacity of the lithium ion secondary battery displayed on the electric vehicle or the electric vehicle based on the battery remaining capacity. The state detection system of the lithium ion secondary battery of Claim 4 which has a 2nd update means to update the driving | running | working possible distance.   The state detection system of the lithium ion secondary battery according to any one of claims 1 to 5, wherein the discharging unit supplies the discharged power to the house as the external load as power used in the house. . (A) detecting that the SOC of the lithium ion secondary battery mounted on the electric vehicle is 0%;
Discharging the lithium ion secondary battery until it is detected in step (a) that the SOC of the lithium ion secondary battery is 0%, and supplying the discharged power to an external load (b) When,
Charging the lithium ion secondary battery until the SOC of the lithium ion secondary battery reaches a predetermined value after the lithium ion secondary battery is discharged in the step (b);
In the step (c), in a state where the lithium ion secondary battery is charged until the SOC reaches the predetermined value, a current is applied to the lithium ion secondary battery, and the lithium ion obtained by applying the current is applied. Calculating a battery resistance of the lithium ion secondary battery by measuring a voltage change of the secondary battery (d);
Determining a deterioration state of the lithium ion secondary battery based on the battery resistance calculated in the step (d);
A state detection method for a lithium ion secondary battery.   The state detection method of a lithium ion secondary battery, wherein the predetermined value of the SOC is 100%.   The state detection method of the lithium ion secondary battery according to claim 7 or 8, wherein the current applied to the lithium ion secondary battery in the step (d) is a pulse current.   The battery resistance data calculated in the step (d) is transmitted to the electric vehicle, and the battery resistance data of the electric vehicle is further updated (f). The state detection method of the lithium ion secondary battery as described in any one.   The electric vehicle is based on the battery resistance data updated in the step (f), the remaining battery capacity of the lithium ion secondary battery displayed on the electric vehicle, or the electric vehicle based on the remaining battery capacity. The state detection method of the lithium ion secondary battery of Claim 10 which further has the step (g) of updating the driving | running | working possible distance.   The state of the lithium ion secondary battery according to any one of claims 7 to 11, wherein in the step (b), discharged electric power is supplied to the house as the external load as electric power used in the house. Detection method.